Microsoft Corporation
LOW-COST LINEAR ORDERS FOR QUANTUM-PROGRAM SIMULATION

Abstract:

In a method to digitally simulate an evolving quantum state of a qubit register of a quantum computer, the quantum state is represented as a state vector of complex-valued amplitudes, where each amplitude is associated with an individual qubit of the qubit register. A directed acyclic graph defining a set of quantum gates of a quantum-computer program is then received. A linear order for the DAG is constructed by minimizing a partial cost function successively re-computed during construction of the linear order, the partial cost function approximating a cost of transforming the state vector according to a subset of the set of quantum gates applied in the linear order. The state vector is transformed according to the set of quantum gates applied in the linear order, and one or more of the complex-valued amplitudes of the transformed state vector are computationally output.